Organic farming practices generally improve the environment in several ways: 1) Organic systems build up soil quality over time by increasing soil organic matter and biological activity through the use of cover crops, compost, and manure rather than synthetic fertilizers. 2) Organic practices reduce water pollution, with studies finding lower nitrogen leaching and reduced nitrogen losses in tile drainage water compared to conventional systems. 3) While organic systems may use more fuel for cultivation, life cycle assessments have found lower total carbon dioxide emissions from organic farms due to fewer synthetic nitrogen inputs.

1. Ben Bowell
Organic Education Specialist, Oregon Tilth
Organic Conservation Specialist, USDA NRCS
NRCS West National Technology Support Center

2. OUTLINE
Is Organic Environmentally
Friendly?
• USDA Organic
• Soil
• Water
• Climate & Energy
• Biodiversity

3. Organic practices “must maintain or
improve the natural resources of the
operation, including soil and water
quality.”
§205.200
Organic agriculture is a “production system
that ….. promote(s) ecological balance, and
conserve(s) biodiversity.”

4. Soil fertility & nutrient
management
• maintain or improve the…condition of soil and
minimize soil erosion
• maintain or improve soil organic matter
content…
Alfalfa

5. Crop Rotation
Photo: Jen Miller

6. Pest Management
Photo: SABeebe (bugguide.net)

7. Comments on Research
• Organic producers limited in practices, but
conventional producers can use “organic” practices
• Difficult to discuss without comparison to conventional
• Wide variation in practices and farming systems
• Limited research; focus on broad trends and available
research

8. USDA National Organic Program Standard 205.2
“A production system that ….. promote(s)
ecological balance, and conserve(s) biodiversity.”Soil

9. Soil
Generally studies report:
• Organic systems preserve or improve soil quality
• biophysical (e.g., SOM) and biological (e.g., biodiversity)
• Organic farming is usually associated with a higher level of
biological activity (total microbial abundance and activity,
bacteria, fungi, earthworms, etc)
• Organic management results in higher soil water-holding
capacity (inc yield in drought)
“Environmental Impact of Different Agricultural Management Practices: Conventional vs. Organic Agriculture.” Critical Reviews
in Plant Science, 2011
“Organic farming enhances soil microbial abundance and activity: A meta-analysis and meta-regression.” PLoS ONE, 2017

10. • Examine long-term impact of organic rotations/systems
• 6 of the oldest grain-crop-based organic in the U.S.
initiated in 1980’s and 90’s in PA, CA, MN, WI, MD, IA
• Multiple organic rotations range from 3-10 yrs
“A Review of Long-Term Organic
Comparison Trials in the U.S.”
Sustainable Agriculture Research, 2015
Long-Term Trials

11. General
Trends
Service/Characteristic Comparison
Crop Yield Conv > Org
Soil Erosion NT < Org < CT
Net Returns Conv < Org
Soil Carbon Conv < Org
Soil Fertility Conv < Org
Fertilizer Use Conv > Org
Dr. Michel Cavigelli, USDA ARS

12. Keys to success/findings:
• Additions of OM
• Manure & legume forage/cover crops
• Extended and diverse crop rotations
• fertility, lower weed pressure, reduce
soil erosion
• SOC & potentially mineralizable N
greater in longer rotations (i.e. 6-yr
with alfalfa v. 3-yr w/o alfalfa)
• Soil quality is the main driver of yields
• Fertility/mineralization & soil quality
“A Review of Long-Term Organic Comparison Trials in the U.S.”
Sustainable Agriculture Research, 2015
Long-Term Trials
Alfalfa

13. Water
NRCS

14. Water
Few studies on water quality in organic systems, water quality
monitoring infrastructure can be expensive.
Findings indicate:
• Adding perennials to the crop rotation reduce N and P loads
• Organic practices can significantly reduce N leaching (23% in
one study, 40% in another)
“Water quality in organic systems.” Sustainable Agriculture Research, 2015

15. Organic rotations (perennial and OM
N source?) reduced tile nitrate
concentrations and reduce N loss in
tile drainage water
• Organic C-S-O/A-A: between 3-8%
of applied N loss/year
• Conv C-S: between 12-40% of
applied N loss/year
Dairy compost for organic;
conventional tillage for org & conv
Organic Water Quality Research
Boone, IA
Dr. Cynthia A. Cambardella, USDA-ARS

16. The Rodale FST
Kutztown, PA
• Water leaching (lysimeter) from
the Cnv more frequently
exceeded the legal limit (10 ppm)
for nitrate-N concentrations in
water compared to the Org
systems
– (20% of cnv samples v. 15% in org
legume & 8% in org manure)
Rotations: Cnv NT, Cnv Tilled, Org NT &
Tilled legume (4yr), Org NT & Tilled
manure (8-10 yr)
Dr. Kris Nichols, Rodale Institute

17. Phosphorus?
• P build up over time with
manure/compost for N?
• Credit mineralization in N
budget?
• N from cover crops (ex: Rodale)
PAN P2O5 K2O
Vegetable crop 150 60 170
3.5 tons chicken
manure 145 210 210

18. Climate & Energy

19. Climate & Energy
In Life Cycle Impact
Assessments (include
embedded emissions ex:
fertilizer), total C02
emissions found to be
lower in organic systems
due to reduced N inputs
(despite increased fuel
use / tillage)
“Modeling carbon cycles and estimation of greenhouse gas emissions from organic
and conventional farming systems.” Renewable Agriculture and Food Systems, 2007

20. The Wisconsin Integrated Cropping
Systems Trial: CO2 Emissions
0
200
400
600
800
1000
1200
1400
1600
1800
1 2 3 4 5 6
cont .corn NT c-sb org c-soy-wht green gold alf org c-oat/alf-alf pasture
grain dairy
kgCO2eq/ha/yr
misc
pestic
manure
fert
graindry
diesel
Dr. Erin Silva, University of Wisconsin
Cvt corn &
3 yr alf

21. Carbon Sequestration
• Meta-analysis of ~75 studies
• Organic farming practices lead to
increased SOC stocks in the upper
20 cm of soil
• SOC stocks were 3.50 ± 1.08 Mg C
ha−1 higher
• External carbon inputs (compost,
manure) and crop rotations likely
contributed to increase in organic
systems
“Enhanced top soil carbon stocks under organic farming.” Proceedings of the
National Academy of Sciences of the United States of America/PNAS, 2012

22. Tillage?
NRCS

23. The Beltsville FSP
• Despite negative impact of tillage, total
SOC greater in all organic systems than
in the cnv NT
• SOC distribution with depth:
– Generally: in surface 5 cm, SOC is greater in
NT
– The SOC was greater in the ORG 6-yr rotation
compared to NT at all depths except 0 to 5 cm
• C-S rotations (w/ cover crops): NT (3yr), Tilled
(3yr), Org (2yr), Org (3yr), Org (6yr w/ 3yr A)
Dr. Michel Cavigelli, USDA-ARS

24. USDA National Organic Program Standard 205.2
“A production system that ….. promote(s)
ecological balance, and conserve(s) biodiversity.”
NRCS; nighthawk
Biodiversity

25. Biodiversity
“Land-use intensity and the effects of organic farming on biodiversity: a
hierarchical meta-analysis.” Journal of Applied Ecology, 2014
Analysis of ~100 studies:
• On average, organic farming increased species
richness by about 30%
• Greatest increases: plants (~75%) and pollinators
(~50%)
• In terms of crop production types, greatest
difference was in cereal production (organic
+40%)

26. Biodiversity
“Biodiversity and organic farming: what do we know.” Landbauforschung Volkenrode, 2011
Increased biodiversity in organic systems:

27. Summary
In general, organic farming is
environmentally friendly. But better
when systems:
• Focus on soil quality – add
biomass, compost/manure. SOM
can provide fertility
• Have more diversity / crops
• Include cover crops, inc legumes
(N, biomass)
• Have longer rotations – possibly
with pasture or perennials (reduce
tillage, fertility)

28. Ben Bowell
ben@tilth.org
benjamin.bowell@por.usda.gov
503-580-4767
Questions?